<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .active {
            color: red;
        }
    </style>
</head>

<body>
    <div id="app">
        <ul>
            <li v-for='(item, index) in navList' @click='handleToClick(index)'
                :class='index === current ? "active" : ""'>{{item}}</li>
        </ul>
    </div>

    <script src='./js/vue.js'></script>
    <script>
        let vm = new Vue({
            el: '#app',
            data: {
                navList: ['首页', '产品', '关于我们'],
                current: 0
            },
            methods: {
                handleToClick(index) {
                    this.current = index
                }
            }
        })
    </script>
</body>

</html>